Arachidonic acid-dependent metabolism of (+/-)-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene to polyguanylic acid-binding derivatives.

Microsomal and solubilized enzyme preparations from ram seminal vesicles catalyze the oxidation of (+/-)-7,8-dihydroxy-7,8-dihydrobenzo[alpha]-pyrene (BP-7,8-diol) to derivatives which covalently bind to polyguanylic acid (poly(G)). Oxidation requires prostaglandin endoperoxide synthetase and its substrate arachidonic acid and is inhibited by indomethacin. High performance liquid chromatographic (HPLC) analysis of the nucleoside adducts obtained following chemical and enzymatic digestion reveals an adduct pattern which is identical to that obtained by the reaction of poly(G) with (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene (diol-epoxide 2). The ratios of the diastereomeric pairs of cis- and trans-diolepoxide 2-guanosine adducts indicate that both enantiomers of (+/-)-BP-7,8-diol are metabolized to an equal extent.